This invention relates to modular barriers of the type used in crowd and traffic control.
Conventional modular traffic control barriers consist of a number of barrier sections made from cast concrete. Each barrier section has a comparatively narrow upright portion surmounted by a comparatively wide base portion. Metallic ties are cast into the concrete and project from both ends of the upright portion of the barrier section. When two barrier sections are placed side-by-side, the metallic ties line up and can be bolted through, thus attaching the barrier sections to one another and at the same time forming a makeshift hinge. By means of the hinge, the two barrier sections can be articulated relative to one another, allowing the completed barrier to follow a serpentine path if desired.
Similar designs are in use for crowd control barriers. An example is described in U.S. Pat. No. 5,836,714. The barrier in question is particularly well illustrated in FIG. 9 of that document. The barrier is modular, being constructed of a series of substantially identical barrier sections. Each section is articulated to an adjacent section or two adjacent sections by means of a pin that passes through shaped projections in the sections. Upper and lower shaped projections are formed at one end of each section and a median shaped projection is formed at the other end. In this way, the pin passes through an upper projection of one section, a median projection of an adjacent section and then the lower projection of the first section. Each section is ramp-shaped and lies almost entirely to one side of the line drawn between the two articulating pins of the section in question. This arrangement allows the barrier to bend in one direction, opening up a gap between the adjacent ramp-shaped sections, but does not permit it to bend in the other direction.
A modular traffic control barrier in which adjacent sections are connected to one another by a pin is described in U.S. Pat. No. 4,681,302. However, this barrier is one in which no articulation of the sections relative to one another is possible. Instead, if a bend is required in the barrier, shaped inserts and additional connecting pins have to be introduced between sections. FIGS. 5-8 of the document illustrate a number of configurations that can be achieved with such inserts.
A more flexible modular traffic control barrier is described in international patent application no. WO99/53145. Here the barrier sections, viewed in plan, have a semicircular nose at one end and a corresponding semicircular recess at the other. However, because of its shape, the barrier is of uniform width rather than possessing a wide base and a narrow upright portion, which means that either it is very wide or it is likely to fall over. The noses and recesses mean that adjacent barrier sections may be placed at an angle to each other. UK patent application no. GB 2,292,404 A describes something similar.
Traffic control barriers tend to be made of heavy, impact-resistant materials such a concrete, because of the very high lateral impact forces that need to be withstood. Crowd control barriers on the other hand tend to be made of relatively light materials and are not required to be impact-resistant. These contradictory requirements have led to the development of different classes of barriers.